In dealing with the trinity there are certain sources that say that the Roman Catholic church invented the belief in the trinity during a specific council.I want to have reliable proof.

No, the Church council, it was all the chiristians of all the various parts of the Church, there the Bishop of Rome was one of them, but he was only one of the many Bishops at the Coucils.

The Church Councils settled issues of teachings, which was the role of the Coucils, ( remember the Bishops of the various groups were the ones conisdered to be the replacements of the original Apostles.
And just as they meet and decided things for the Church, in the early Church for the first 800 years, the early church had the Bishops of the major Churches meet and decide many things.

The early councils decided what books are in the bible,
The set up the Apostles Creed and the other creeds of the church, still used in many churches.

And the issue of the Trinity was also finalised there also. The majority of all the church believed in it, but there was no formal doctrine at the time, and this was an issued settled then.
So it was not the Roman Church, since their Bishop was merely one of many who was at the Councils that decided all of this.

For example the Orthodox Church still teaches they were the head of these early councils, remember the church of the east ( orthodox) and the church of the west ( Rome) were not divided at this time
COUNCILS OF THE CHURCH | Antiochian.org

MAJOR COUNCILS OF THE CHURCH: (councils.htm)

CATHOLIC ENCYCLOPEDIA: General Councils

Padre ;Great response!!